The vulnerable UPnP stack is used in many routers based on Broadcom chipsets, DefenseCode researchers say.

However, customers who wish to disable the UPnP functionality in Linksys routers can follow the instructions in a technical support document published earlier this week in response to the UPnP vulnerabilities reported by Rapid7.

DefenseCode focused its investigation of this vulnerability on routers, but if the Broadcom UPnP stack is also used in other network-enabled devices like printers, media servers, IP cameras and smart TVs, then those devices are probably vulnerable as well, Juranic said. "But we didn't research other devices, so we can't be sure," he said.

Rapid7 researchers said Monday in their UPnP research paper that more than 15 million devices that responded to UPnP requests from the Internet were using "a commercial stack that is likely developed by Broadcom." They referred to this implementation as "Unknown SDK 1" and said that it was the third most commonly used UPnP stack after Intel/Portable UPnP SDK and MiniUPnP SDK.

Juranic is confident that "Unknown SDK 1" from Rapid7's paper is the vulnerable Broadcom UPnP SDK identified by DefenseCode.

Rapid7 did not immediately respond to a request to confirm this on Friday, but a Thursday Twitter message from HD Moore, Rapid7's chief security officer, suggests that Juranic is correct. "DefenseCode identified a format string in the Broadcom UPnP SOAP service (around ~15m hosts as identified by Rapid7)," he wrote.

However, though having the UPnP service exposed to the Internet increases the chances of a device being attacked, it is not a prerequisite for exploiting the vulnerability found by DefenseCode or the ones found by Rapid7 in UPnP implementations. An attacker who gains access to a local network can also exploit these vulnerabilities to hack into UPnP-enabled networked devices.

Juranic advised all users to disable UPnP in their routers because the risks outweigh the benefits of having the service enabled. "At the moment, there is no reason to have router UPnP enabled, since it's probably vulnerable to one of the discovered UPnP security vulnerabilities," he said.